Computer network management is an extensively studied field. Many architectures, management schemes, communication protocols, and hardware platforms are readily available, but those are largely based on the assumption that the network is terrestrial. Not all networks are and the situs of the network can be very important. While there are many similarities between terrestrial and space-based networks, there are unique features that limit the applicability of a terrestrial network management system (NMS) to a space-based NMS. Specifically, a space-based NMS, being isolated, must maintain a high level of reliability and availability notwithstanding the increased environmental impacts encountered in space. In addition, the space-based NMS must recover quickly and autonomously. Therefore, robustness, redundancy and autonomy are central to the implementation of an effective space-based NMS.
Redundancy is a straightforward matter in design implementation to meet spacecraft reliability requirements. The redundancy may be a 2:1, 3:2, or other ratio, wherein the first number indicates the total number of components or systems and the second is the number required to be active at any one time for normal operation. A much more subtle issue is the state of each back-up component or system, which can run from active-monitoring, to hot-standby, and to cold-standby.
Security is of course another consideration, and an important one for terrestrial networks—a terrestrial NMS could potentially be comprised through the Internet. Security is also an important consideration for space-based networks, but less so, especially for an intra-spacecraft network where access is extremely limited and the space-ground connection is secure. Therefore, security internal to the intra-spacecraft network is not a necessary requirement of every space-based NMS.
In most cases, space-based networks are not accessible by humans. While this limitation increases the need for redundancy, it also adds complexities that are not seen in terrestrial networks but that must be overcome. For example, the space-based NMS must autonomously recover from an unforeseen software failure since a human may not be available to press a reset button, for example.
Component choice is clearly important in any network design but especially so in space-based networks. When compared to a terrestrial network, network components on a spacecraft are constructed with proven technologies, which tend to be older, larger, heavier, and to have power limitations that newer technology has improved. Newer components that would appropriately support a terrestrial NMS are not appropriate for a space-based NMS simply because they have not demonstrated they meet the reliability requirements dictated by the increased environmental impacts that affect space-based NMS.
Network Management systems may have a centralized or a distributed architecture. In a management architecture that is centralized, all of the management tasks are located in one area, but in a distributed architecture, management tasks are spread throughout the network. The lack of human intervention and the need for quick recovery are driving factors for a spacecraft network management system (SNMS) to have a distributed network architecture. In addition, because a network within a satellite is not capable of being repaired by a human like a terrestrial network, the SNMS is also improved if redundant systems are located in different units, boards, or sections of a board. Finally, in the event of a failure of the SNMS, the redundant portion of the SNMS must become active immediately to meet space-based performance requirements and to support spacecraft safety functions.
A network management system that is reliable, has high availability, is robust to the space environment, and is able to function autonomously would be advantageous as a spacecraft network management system.